Beaufort number |
Wind speed |
Mean wind speed |
Description |
Wave height |
Sea conditions |
Land conditions |
||||
| kt | km/h | mph | m/s | kt / km/h / mph | m | ft | ||||
| 0 | 0 | 0 | 0 | 0-0.2 | 0 / 0 / 0 | Calm | 0 | 0 | Flat. | Calm. Smoke rises vertically. |
| 1 | 1-3 | 1-6 | 1-3 | 0.3-1.5 | 2 / 4 / 2 | Light air | 0.1 | 0.33 | Ripples without crests. | Wind motion visible in smoke. |
| 2 | 4-6 | 7-11 | 4-7 | 1.6-3.3 | 5 / 9 / 6 | Light breeze | 0.2 | 0.66 | Small wavelets. Crests of glassy appearance, not breaking | Wind felt on exposed skin. Leaves rustle. |
| 3 | 7-10 | 12-19 | 8-12 | 3.4-5.4 | 9 / 17 / 11 | Gentle breeze | 0.6 | 2 | Large wavelets. Crests begin to break; scattered whitecaps | Leaves and smaller twigs in constant motion. |
| 4 | 11-16 | 20-29 | 13-18 | 5.5-7.9 | 13 / 24 / 15 | Moderate breeze | 1 | 3.3 | Small waves. | Dust and loose paper raised. Small branches begin to move. |
| 5 | 17-21 | 30-39 | 19-24 | 8.0-10.7 | 19 / 35 / 22 | Fresh breeze | 2 | 6.6 | Moderate (1.2 m) longer waves. Some foam and spray. | Smaller trees sway. |
| 6 | 22-27 | 40-50 | 25-31 | 10.8-13.8 | 24 / 44 / 27 | Strong breeze | 3 | 9.9 | Large waves with foam crests and some spray. | Large branches in motion. Whistling heard in overhead wires. Umbrella use becomes difficult. |
| 7 | 28-33 | 51-62 | 32-38 | 13.9-17.1 | 30 / 56 / 35 | Near gale | 4 | 13.1 | Sea heaps up and foam begins to streak. | Whole trees in motion. Effort to walk against the wind. |
| 8 | 34-40 | 63-75 | 39-46 | 17.2-20.7 | 37 / 68 / 42 | Gale | 5.5 | 18 | Moderately high waves with breaking crests forming spindrift. Streaks of foam. | Twigs broken from trees. Cars veer on road. |
| 9 | 41-47 | 76-87 | 47-54 | 20.8-24.4 | 44 / 81 / 50 | Strong gale | 7 | 23 | High waves (2.75 m) with dense foam. Wave crests start to roll over. Considerable spray. | Light structure damage. |
| 10 | 48-55 | 88-102 | 55-63 | 24.5-28.4 | 52 / 96 / 60 | Storm | 9 | 29.5 | Very high waves. The sea surface is white and there is considerable tumbling. Visibility is reduced. | Trees uprooted. Considerable structural damage. |
| 11 | 56-63 | 103-117 | 64-72 | 28.5-32.6 | 60 / 111 / 69 | Violent storm | 11.5 | 37.7 | Exceptionally high waves. | Widespread structural damage. |
| 12 | >63 | >117 | >72 | >32.7 | N/A | Hurricane | 14+ | 46+ | Huge waves. Air filled with foam and spray. Sea completely white with driving spray. Visibility very greatly reduced. | Massive and widespread damage to structures. |
Updated: Saturday, October 4, 2014 8:59